CN108998759B - A method for improving indirect bandgap luminescence properties of multilayer molybdenum disulfide thin films - Google Patents

Abstract

The invention discloses a method for improving the indirect band gap luminescence performance of a multilayer molybdenum disulfide thin film, which comprises depositing platinum nanoparticles on the surface of the multilayer molybdenum disulfide thin film by a physical vapor deposition method, and the particle size of the platinum nanoparticles is less than 10 nanometers; The particle size with platinum nanoparticles is less than 10 nanometers, which can improve the indirect bandgap luminescence performance of the multilayer molybdenum disulfide thin film. Compared with the pure multilayer molybdenum disulfide thin film, the indirect bandgap luminescence performance is improved, and is better than that of silver nanoparticles The improvement of the indirect band gap luminescence performance of the multilayer molybdenum disulfide film is beneficial to improve the sensitivity of the photodetector.

Description

A method for improving indirect bandgap luminescence properties of multilayer molybdenum disulfide thin films

technical field

The invention relates to the technical field of photodetectors and fluorescent markers, in particular to a method for improving the indirect band gap luminescence performance of a multilayer molybdenum disulfide thin film.

Background technique

As a research hotspot in recent years, molybdenum disulfide has attracted extensive attention of researchers due to its unique structure and excellent properties. Molybdenum sulfide two-dimensional materials have great application potential in the field of optoelectronic devices due to their tunable band gap and good light absorption.

The optical properties of molybdenum disulfide materials have been studied systematically. In the light absorption experimental study, it was found that two distinct absorption peaks were observed at 1.88 eV (A peak) and 2.06 eV (B peak) for the bulk material molybdenum disulfide, which were attributed to the split from the K point in the Brillouin zone. In the experimental study of photoluminescence, it is found that the optical properties of molybdenum disulfide are closely related to the thickness of the layers. The luminescence signal is weak and belongs to the indirect bandgap semiconductor, which corresponds to the characteristic luminescence peak of the indirect bandgap transition of 1.4 eV at 890 nm. There are characteristic peaks of A and B direct bandgap transitions corresponding to 1.85 eV and 1.97 eV around 670 nm and 630 nm. When the thickness of the molybdenum disulfide material is reduced to a single layer, the molybdenum disulfide changes from an indirect bandgap semiconductor to a direct bandgap semiconductor, and the photoluminescence signal is enhanced. The widening of the forbidden band width leads to a gradual increase in the photoluminescence quantum efficiency. There are characteristic luminescence peaks corresponding to the direct bandgap transition of A and B excitons at 1.85 eV and 1.97 eV near 670 nm and 630 nm, respectively. The A and B characteristic peaks are considered to be caused by the splitting of the valence band spin-orbit energy level at the K point. , and the peak position corresponds to the peak position of the absorption peak.

In recent years, there has been some research on improving the photoluminescence of monolayer molybdenum disulfide, and the chemical method is a simple and easy technique by controlling the carrier concentration: Shinichiro Mouri exploits the higher electron affinity of p-type doping The photoluminescence intensity and peak position of the monolayer molybdenum disulfide can be tuned by TFSI; Matin Amani used TFSI to fill the edge S vacancies of the chemically exfoliated molybdenum disulfide, thereby greatly improving the photoluminescence of the monolayer molybdenum disulfide. performance. The plasmon resonance effect is to obtain a localized surface plasmon resonance spectrum by using metal nanoparticles to exhibit very small spectral absorption in the ultraviolet and visible light bands. The absorption wavelength at the peak of the spectrum depends on the microstructural properties of the material, such as composition and shape. ,structure size. Noble metal plasmonic nanostructures, represented by gold and silver, serve as an effective method to enhance 2D materials with inherently low absorption and emission. SerkanButun fabricated silver nanoparticle arrays by electron beam lithography, and improved the direct bandgap luminescence performance of monolayer molybdenum disulfide by 12 times by adjusting the size of silver nanoparticles (silver nanoparticle size in the range of 106-227nm). There is also Min-Gon Lee using A platinum MS to couple gold nanoparticles and transferred monolayer molybdenum disulfide films (gold nanoparticle size in the range of 40-113 nm). However, these all focus on improving the size-limited sheet-like monolayer MoS2, which will be limited in large-area photoluminescence research, and there is little research on improving the indirect bandgap luminescence of multilayer MoS2 thin films. . Therefore, in order to meet the needs of arrayed photodetectors, it is of special significance to develop a multilayer molybdenum disulfide thin film material with high indirect band gap luminescence and good uniformity and its preparation method.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is that the indirect band gap of the multilayer molybdenum disulfide thin film is rarely explored, and a new multilayer molybdenum disulfide thin film material with high indirect band gap luminescence and good uniformity and a preparation method thereof are provided, The preparation method is convenient, easy, and low in cost, and is suitable for batch development of arrayed devices.

A method for improving the indirect band gap luminescence performance of a multilayer molybdenum disulfide thin film comprises depositing platinum nanoparticles on the surface of the multilayer molybdenum disulfide thin film by a physical vapor deposition method, and the particle size of the platinum nanoparticles is less than 10 nanometers.

Further limited, the physical vapor deposition method is a magnetron sputtering method or an electron beam evaporation method.

Further limited, the multilayer molybdenum disulfide film is prepared by the following steps:

1) Preheat the substrate in a vacuum environment of 100-120°C for 30-45 minutes;

2) Under the working pressure of 0.5-1.0Pa, the molybdenum target is pre-sputtered for 10-15 minutes in an atmosphere of pure argon;

3) Using the atmosphere of pure argon, under the working pressure of 0.5-1.0Pa, the pre-sputtered molybdenum target in step 2) is sputtered to the pre-heated substrate in step 1) to deposit a molybdenum film. The thickness of the film is 1.8-2.5 nanometers;

4) Chemical vapor deposition of the molybdenum film in step 3) is carried out in a tube furnace, wherein the sulfur powder is upstream of the heating source in the tube, the molybdenum film is downstream of the heating source in the tube, and the pressure in the tube is 10Pa-100Pa. Always keep the flow rate of sulfur steam at 5-20sccm;

5) In a vacuum environment, the molybdenum film in step 4) is preheated at 110-130°C for 50-60 minutes, and the sulfur powder in step 4) is preheated at 80-100°C for 50-60 minutes ;

6) The tube furnace in step 4) is heated to a reaction temperature of 550°C-750°C, the reaction time of the sulfur powder and the molybdenum film is 20-30 minutes, and the annealing time is 60-120 minutes.

Further limited, the specific operation steps of the magnetron sputtering method are as follows:

a) baking the multilayer molybdenum disulfide film at 100-150°C for 15-60 minutes in a sputtering chamber with a background vacuum greater than 4×10 ^-3 Pa;

b) Pre-sputtering the platinum target for 10-15 minutes under the working pressure of 6.0-9.0Pa in an atmosphere of pure argon;

c) Using pure argon atmosphere, under the working pressure of 0.5-1.5Pa, with the target current density of 0.2-1mA/ ^cm2 , deposit the platinum nanoparticles on the multilayer molybdenum dioxide film, and the deposition time is 18 -36 seconds;

d) heating the multi-layer molybdenum disulfide film deposited with platinum nanoparticles obtained in step c) to 200-260° C. in a vacuum environment, and annealing at a low temperature for 30-60 minutes;

e) Naturally cooling the multilayer molybdenum disulfide film obtained after the low temperature annealing in step d) to normal temperature in a vacuum environment.

Further limited, the specific operation steps of the electron beam evaporation method are as follows:

1. Bake the multilayer molybdenum disulfide film at 100-150°C for 15-60 minutes in a vacuum chamber with a background vacuum degree greater than 4×10 ^-3 Pa;

II. In the atmosphere of pure argon, using a tungsten evaporation boat, under the working pressure of 4×10 ^-4 Pa, pre-evaporate the platinum target for 10-15 minutes;

III. The baffle of the tungsten evaporation boat in step II is opened, the real-time evaporation power is controlled between 200w-300w, and the platinum nanoparticles are deposited on the multilayer molybdenum dioxide film, and the deposition time is 18-36 seconds;

IV. The multi-layer molybdenum disulfide film deposited with platinum nanoparticles obtained in step III is heated to 200-260° C. in a vacuum environment, and annealed at a low temperature for 30-60 minutes;

V. The multi-layer molybdenum disulfide film obtained after the low temperature annealing in step IV is naturally cooled to normal temperature in a vacuum environment.

Further limited, the mass fraction of molybdenum in the molybdenum target is greater than 99.9%, and the mass fraction of sulfur in the sulfur powder is greater than 99.9%.

Further defined, the mass fraction of platinum in the platinum target is 99.9%.

The beneficial effects of the present invention are:

1. Physical vapor deposition of platinum nanoparticles on the surface of the multilayer molybdenum disulfide film, the particle size of the platinum nanoparticles is less than 10 nanometers, which can improve the indirect bandgap luminescence performance of the multilayer molybdenum disulfide film, compared with pure multilayer The molybdenum disulfide film has improved indirect bandgap luminescence performance, which is better than that of silver nanoparticles in the improvement of the indirect bandgap luminescence performance of the multilayer molybdenum disulfide film, which is beneficial to improve the sensitivity of the photodetector.

2. The magnetron sputtering method or the electron beam evaporation method can sputter the platinum nanoparticles on the platinum target into particles with a particle size of less than 10 nanometers, and the platinum nanoparticles can be uniformly deposited on the multilayer molybdenum disulfide thin film. It is suitable for the deposition of large-area multi-layer molybdenum disulfide thin films on the surface and improves the indirect band gap luminescence of the multi-layer molybdenum disulfide thin films.

3. The preparation method of the multi-layer molybdenum disulfide film, the prepared molybdenum disulfide film has good uniformity and large area, which is conducive to detecting the deposition effect of magnetron sputtering or electron beam evaporation on platinum nanoparticles, and expanding the magnetic field. The scope of application of controlled sputtering or electron beam evaporation.

4. The mass fraction of platinum in the molybdenum target is greater than 99.9%, the mass fraction of sulfur in the sulfur powder is greater than 99.9%, and the mass fraction of platinum in the platinum target is 99.9%; making the indirect band gap of the multilayer molybdenum disulfide thin film The luminescence properties are 7-16 times higher than the indirect bandgap luminescence properties of pure multilayer molybdenum disulfide thin films.

Description of drawings

Fig. 1 is the flow chart of the present invention;

Fig. 2 is the emission spectrum of the multilayer molybdenum disulfide film with platinum nanoparticles and the multilayer pure molybdenum disulfide film prepared in Example 1;

Fig. 3 is the emission spectrum of the multilayer molybdenum disulfide film with platinum nanoparticles and the multilayer pure molybdenum disulfide film prepared in Example 2;

4 is the emission spectrum of the multilayer molybdenum disulfide film with platinum nanoparticles and the multilayer pure molybdenum disulfide film prepared in Example 3;

Fig. 5 is the emission spectrum of the multilayer molybdenum disulfide film with platinum nanoparticles and the multilayer pure molybdenum disulfide film prepared in Example 4;

6 is the emission spectrum of the multilayer molybdenum disulfide film with platinum nanoparticles and the multilayer pure molybdenum disulfide film prepared in Example 5;

FIG. 7 is the emission spectrum of the multilayer molybdenum disulfide film with platinum nanoparticles and the multilayer pure molybdenum disulfide film prepared in Example 6. FIG.

Detailed ways

In order for those skilled in the art to understand the production process and technical effects of the present invention in detail, the application and technical effects of the present invention are further introduced below with specific production examples.

Example 1:

Preheat the substrate (SiO2/Si or quartz glass) in a vacuum environment at a temperature of 100-120°C for 30-45 minutes; then use a pure argon atmosphere and under a working pressure of 0.5-1.0Pa, the molybdenum target Carry out pre-sputtering for 10-15 minutes; then, using pure argon atmosphere, under the working pressure of 0.5-1.0Pa, sputter-deposit molybdenum film on the preheated substrate, the sputtering current is 0.1A, and the deposition time is 11 seconds; the deposited molybdenum film was chemically vapor deposited in a tube furnace, wherein the sulfur powder was upstream of the heating source in the tube, the molybdenum target was downstream of the heating source in the tube, the pressure in the tube was 10Pa, and argon was used to remove air and Accelerate the movement of the gasified sulfur vapor, thereby promoting the reaction between molybdenum and sulfur, and keep the flow rate of argon at 5 sccm before and after the reaction; Preheat at ℃ for 50-60 minutes; heat up the tube furnace to the reaction temperature of 550-750 ℃, the reaction time is 20-30 minutes, and the annealing time is 60-120 minutes; then the multilayer molybdenum disulfide film is placed in a vacuum environment. , the temperature is 100-150 ℃ baking for 15-60 minutes; using pure argon atmosphere, under the working pressure of 6.0-9.0Pa, the platinum target is pre-sputtered for 10-15 minutes; then, using pure argon gas Atmosphere, under the working pressure of 0.5-1.5Pa, with the target current density of 0.2mA/cm2, deposition for 18 seconds. Finally, the multi-layer molybdenum disulfide film deposited with platinum nanoparticles was heated to 200-260 °C in a vacuum environment, and annealed at a low temperature for 30-60 minutes, and then the annealed multi-layer molybdenum disulfide film was naturally cooled in a vacuum environment to At room temperature, a multilayer molybdenum disulfide film with high indirect bandgap luminescence properties is obtained, which is recorded as platinum-MoS2-0.55-1;

As a comparative example, at the same time, a molybdenum target (with a molybdenum content of 99.9%) was used as the sputtering source, and the sulfur powder (with a sulfur content of 99.9%) and a molybdenum target were prepared by chemical vapor deposition under exactly the same process conditions to obtain pure disulfide. Molybdenum thin film, denoted as MoS2-1.

Test: respectively test the photoluminescence spectra of Pt-MoS2-0.55-1 and MoS2-1 thin film samples at room temperature; observe platinum-MoS2-0.55-1 by TEM, observe and count the size of platinum nanoparticles;

Calculation: Statistics of the peak intensities of Pt-MoS2-0.55-1 and MoS2 around 1.5eV, which reflect the indirect bandgap performance, subtract the respective baselines, which are around 1.65eV. The emission spectrum is shown in Figure 1, and the luminescence intensity enhancement ratio of Pt-MoS2-0.55-1 compared to MoS2 was calculated. The results obtained by calculation and TEM particle scale analysis test are shown in Table 1:

Table 1. Indirect bandgap luminescence properties and platinum nanoparticle size of multilayer molybdenum disulfide thin films prepared in Example 1

It can be seen that the indirect bandgap luminescence intensity of the multilayer molybdenum disulfide film containing platinum nanoparticles (Pt-MoS2-0.55-1) is 12.36 times that of the pure molybdenum disulfide film.

Example 2:

Preheat the substrate (SiO2/Si or quartz glass) at 100-120°C for 30-45 minutes in a vacuum environment; then use a pure argon atmosphere and pre-sputter the molybdenum target at a working pressure of 0.5-1.0Pa Sputtering for 10-15 minutes; then, using a pure argon atmosphere, under the working pressure of 0.5-1.0Pa, sputter-deposit a molybdenum film on the preheated substrate, the sputtering current is 0.1A, and the deposition time is 11 seconds; The deposited molybdenum film is chemically vapor deposited in a tube furnace, in which the sulfur powder is upstream of the heating source in the tube, the molybdenum target film is downstream of the heating source in the tube, and the pressure in the tube is about 10Pa. For the reaction of molybdenum target and sulfur powder, the flow rate of argon gas was always kept at 5 sccm before and after the reaction; the temperature of molybdenum target and sulfur powder were preheated at 120°C and 80°C respectively in a vacuum environment for 50-60 minutes; the tube furnace was heated to The reaction temperature is 550-750°C, the reaction time is 20-30 minutes, and the annealing time is 60-120 minutes; then the molybdenum disulfide film is baked at 100-150°C for 15-60 minutes in a vacuum environment; using a pure argon atmosphere, Under the working pressure of 6.0-9.0Pa, the platinum target was pre-sputtered for 10-15 minutes; then, using a pure argon atmosphere, under the working pressure of 0.5-1.5Pa, with a target current of 0.2mA/cm ² Density, deposited for 36 seconds. Finally, the multi-layer molybdenum disulfide film deposited with platinum nanoparticles was heated to 200-260 ° C in a vacuum environment, and annealed at a low temperature for 30-60 minutes. After cooling to room temperature, a molybdenum disulfide thin film with high indirect band gap luminescence performance is obtained, which is denoted as Pt-MoS2-2-1.

As a comparative example, at the same time, a molybdenum target (with a molybdenum content of 99.9%) was used as a sputtering source to obtain a molybdenum target, and the sulfur powder (with a sulfur content of 99.9%) and the molybdenum target were prepared by chemical vapor deposition in exactly the same process conditions A pure molybdenum disulfide thin film was obtained, which was designated as MoS2-1.

Test: The photoluminescence spectra of Pt-MoS2-2-1 and MoS2-1 thin film samples at room temperature were tested respectively; Pt-MoS2-1-1 was observed by TEM, and the size of platinum nanoparticles was observed and counted;

Calculation: Statistics of the peak intensities of Pt-MoS2-2-1 and MoS2 around 1.5eV, which reflect the indirect bandgap performance, subtract the respective baselines, which are around 1.65eV. , the emission spectrum is shown in Figure 1, and the luminescence intensity enhancement ratio of Pt-MoS2-2-1 compared to MoS2 was calculated. The results obtained by calculation and TEM particle size analysis test are shown in Table 2:

Table 2. Indirect bandgap luminescence properties and platinum nanoparticle size of platinum nanoparticles-containing molybdenum disulfide thin films prepared in Example 2

It can be seen that the indirect bandgap luminescence intensity of the multilayer molybdenum disulfide film containing platinum nanoparticles (Pt-MoS2-1-1) is 15.6 times that of the pure molybdenum disulfide film.

Example 3:

Preheat the substrate (SiO2/Si or quartz glass) at 100-120°C for 30-45 minutes in a vacuum environment; then use a pure argon atmosphere and pre-sputter the molybdenum target at a working pressure of 0.5-1.0Pa Sputtering for 10-15 minutes; then, using a pure argon atmosphere, under the working pressure of 0.5-1.0Pa, sputter-deposit a molybdenum film on the preheated substrate, the sputtering current is 0.1A, and the deposition time is 11 seconds; The deposited molybdenum film is chemically vapor deposited in a tube furnace, in which the sulfur powder is upstream of the heating source in the tube, the molybdenum target film is downstream of the heating source in the tube, and the air pressure in the tube is about 10Pa. For the reaction between molybdenum target and sulfur powder, the flow rate of argon gas was always kept at 5sccm before and after the reaction; the molybdenum target and sulfur powder were preheated at 120°C and 80°C for 50-60 minutes in a vacuum environment; the tube furnace was heated to the reaction temperature 550°C-750°C, the reaction time is 20-30 minutes, and the annealing time is 60-120 minutes; then the molybdenum disulfide film is baked at 100-150°C for 15-60 minutes in a vacuum environment; Under the working pressure of 6.0-9.0Pa, the platinum target is pre-sputtered for 10-15 minutes; then, under the working pressure of 0.5-1.5Pa, the target current density of 0.6mA/cm ² is adopted in the atmosphere of pure argon. , Pt nanoparticles were deposited by sputtering on the baked substrate. The sputtering current was 0.1A, and the deposition was performed for 14 seconds. Finally, the samples deposited with platinum nanoparticles were heated to 200-260 °C for low temperature annealing for 30-60 minutes in a vacuum environment, and then the obtained annealed samples were naturally cooled to room temperature in a vacuum environment, that is, a high indirect bandgap luminescence performance was obtained. Molybdenum sulfide film, denoted as Pt-MoS2-3-1.

As a comparative example, at the same time, a molybdenum target (with a molybdenum content of 99.9%) was used as a sputtering source to obtain a molybdenum target, and the sulfur powder (with a sulfur content of 99.9%) and the molybdenum target were prepared by chemical vapor deposition in exactly the same process conditions A pure molybdenum disulfide thin film was obtained, which was designated as MoS2-1.

Test: The photoluminescence spectra of Pt-MoS2-3-1 and MoS2-1 thin film samples at room temperature were tested respectively; Pt-MoS2-3-1 was observed by TEM, and the size of platinum nanoparticles was observed and counted;

Calculation: Statistics of the peak intensities of Pt-MoS2-3-1 and MoS2 around 1.5eV, which reflect the indirect bandgap performance, subtract the respective baselines, which are around 1.65eV. The emission spectrum is shown in Figure 1, and the luminescence intensity enhancement ratio of Pt-MoS2-3-1 compared to MoS2 was calculated. The results obtained by calculation and TEM particle scale analysis test are shown in Table 3:

Table 3. Indirect bandgap luminescence properties and platinum nanoparticle size of platinum nanoparticles-containing molybdenum disulfide thin films prepared in Example 3

It can be seen that the indirect bandgap luminescence intensity of the multilayer molybdenum disulfide film containing platinum nanoparticles (Pt-MoS2-3-1) is 7 times that of the pure molybdenum disulfide film.

Example 4:

Preheat the substrate (SiO2/Si or quartz glass) at 100-120°C for 30-45 minutes in a vacuum environment; then use a pure argon atmosphere and pre-sputter the molybdenum target at a working pressure of 0.5-1.0Pa Sputtering for 10-15 minutes; then, using a pure argon atmosphere, under the working pressure of 0.5-1.0Pa, sputter-deposit a molybdenum film on the preheated substrate, the sputtering current is 0.1A, and the deposition time is 17 seconds; The deposited molybdenum film is chemically vapor deposited in a tube furnace, in which the sulfur powder is upstream of the heating source in the tube, the molybdenum target film is downstream of the heating source in the tube, and the pressure in the tube is about 10Pa. For the reaction between molybdenum target and sulfur powder, the flow rate of argon gas was always kept at 5sccm before and after the reaction; the molybdenum target and sulfur powder were preheated at 120°C and 80°C for 50-60 minutes in a vacuum environment; the tube furnace was heated to the reaction temperature 550℃-750℃, the reaction time is 20-30 minutes. The annealing time is 60-120 minutes; then the samples prepared with the molybdenum disulfide film in advance are baked at 100-150 ℃ for 15-60 minutes in a vacuum chamber with a background vacuum better than 2×10 ^-4 Pa; tungsten evaporation is used Boat, under the working pressure of 4×10 ^-4 , pre-evaporate the platinum target for 10-15 minutes; then, open the baffle, control the real-time evaporation power between 200W-300W, and evaporate and deposit platinum on the baked substrate Nanoparticles, the deposition time was 16 seconds; then, the samples deposited with platinum nanoparticles were heated to 200-260 °C for low-temperature annealing for 30-60 minutes in a vacuum environment; finally, the annealed molybdenum disulfide film was naturally cooled in a vacuum environment to At room temperature, a molybdenum disulfide film with high indirect bandgap luminescence properties can be obtained, which is denoted as Pt-MoS2-0.55-2.

As a comparative example, at the same time, a molybdenum target (with a molybdenum content of 99.9%) was used as the sputtering source, and the sulfur powder (with a sulfur content of 99.9%) and a molybdenum target were prepared by chemical vapor deposition under exactly the same process conditions to obtain pure disulfide. Molybdenum thin film, denoted as MoS2-2.

Test: test the photoluminescence spectra of Pt-MoS2-0.55-2 and MoS2-2 thin film samples at room temperature respectively; observe Pt-MoS2-0.55-2 by TEM, and observe and count the size of platinum nanoparticles;

Calculation: Statistics of the peak intensities of Pt-MoS2-0.55-2 and MoS2 around 1.5eV, which reflect the indirect band gap performance, subtract the respective baselines, which are around 1.65eV, calculate the Pt-MoS2-0.55-2 phase than the luminous intensity enhancement ratio of MoS2. The results obtained by calculation and TEM particle scale analysis test are shown in Table 4:

Table 4. Indirect bandgap luminescence properties and platinum nanoparticle size of platinum nanoparticles-containing molybdenum disulfide thin films prepared in Example 4

The results show that the indirect bandgap luminescence intensity of the platinum-containing nanoparticle molybdenum disulfide film (PtMoS2-0.55-2) is 8.8 times higher than that of the pure molybdenum disulfide film (MoS2-2).

Example 5:

Preheat the substrate (SiO2/Si or quartz glass) at 100-120°C for 30-45 minutes in a vacuum environment; then use a pure argon atmosphere and pre-sputter the molybdenum target at a working pressure of 0.5-1.0Pa Sputtering for 10-15 minutes; then, using a pure argon atmosphere, under the working pressure of 0.5-1.0Pa, sputter-deposit a molybdenum film on the preheated substrate, the sputtering current is 0.1A, and the deposition time is 17 seconds; The deposited molybdenum film is chemically vapor deposited in a tube furnace, in which the sulfur powder is upstream of the heating source in the tube, the molybdenum target film is downstream of the heating source in the tube, and the pressure in the tube is about 10Pa. For the reaction between molybdenum target and sulfur powder, the flow rate of argon gas was always kept at 5sccm before and after the reaction; the molybdenum target and sulfur powder were preheated at 120°C and 80°C for 50-60 minutes in a vacuum environment; the tube furnace was heated to the reaction temperature 550℃-750℃, the reaction time is 20-30 minutes. The annealing time is 60-120 minutes; then the samples prepared with the molybdenum disulfide film in advance are baked at 100-150 ℃ for 15-60 minutes in a vacuum chamber with a background vacuum better than 2×10 ^-4 Pa; tungsten evaporation is used Boat, under the working pressure of 4×10 ^-4 , pre-evaporate the platinum target for 10-15 minutes; then, open the baffle, control the real-time evaporation power between 200W-300W, and evaporate and deposit platinum on the baked substrate Nanoparticles, the deposition time is 32 seconds; then the samples deposited with platinum nanoparticles are heated to 200-260 °C for low temperature annealing for 30-60 minutes in a vacuum environment; finally, the annealed multilayer molybdenum disulfide film is naturally cooled in a vacuum environment At room temperature, a molybdenum disulfide film with high indirect bandgap luminescence properties is obtained, which is denoted as Pt-MoS2-1-2.

As a comparative example, at the same time, a molybdenum target (99.9%) was used as a sputtering source to obtain a molybdenum target, and the sulfur powder (99.9%) and the molybdenum target were prepared by chemical vapor deposition to obtain pure molybdenum disulfide under the exact same process conditions. film, denoted as MoS2-2.

Test: test the photoluminescence spectra of Pt-MoS2-1-2 and MoS2-2 thin film samples at room temperature respectively; observe Pt-MoS2-1-2 with TEM, and observe and count the size of platinum nanoparticles;

Calculation: Statistics of the peak intensities of Pt-MoS2-1-2 and MoS2 around 1.5eV, which reflect the indirect band gap performance, subtract the respective baselines, which are around 1.65eV, calculate the Pt-MoS2-1-2 phase than the luminous intensity enhancement ratio of MoS2. The results obtained by calculation and TEM particle scale analysis test are shown in Table 5:

Table 5. Indirect bandgap luminescence properties and platinum nanoparticle size of platinum nanoparticles-containing molybdenum disulfide thin films prepared in Example 5

The results show that the indirect bandgap luminescence intensity of the platinum-containing nanoparticle molybdenum disulfide film (PtMoS2-1-2) is 9.2 times higher than that of the pure molybdenum disulfide film (MoS2-2).

Example 6:

Preheat the substrate (SiO2/Si or quartz glass) at 100-120°C for 30-45 minutes in a vacuum environment; then use a pure argon atmosphere and pre-sputter the molybdenum target at a working pressure of 0.5-1.0Pa Sputtering for 10-15 minutes; then, using a pure argon atmosphere, under the working pressure of 0.5-1.0Pa, sputter-deposit a molybdenum film on the preheated substrate, the sputtering current is 0.1A, and the deposition time is 17 seconds; The deposited molybdenum film is chemically vapor deposited in a tube furnace, in which the sulfur powder is upstream of the heating source in the tube, the molybdenum target film is downstream of the heating source in the tube, and the pressure in the tube is about 10Pa. For the reaction between molybdenum target and sulfur powder, the flow rate of argon gas was always kept at 5sccm before and after the reaction; the molybdenum target and sulfur powder were preheated at 120°C and 80°C for 50-60 minutes in a vacuum environment; the tube furnace was heated to the reaction temperature 550℃-750℃, the reaction time is 20-30 minutes. The annealing time is 60-120 minutes; then the samples prepared with the molybdenum disulfide film in advance are baked at 100-150 ℃ for 15-60 minutes in a vacuum chamber with a background vacuum better than 2×10-4Pa; a tungsten evaporation boat is used , under the working pressure of 4 × 10-4Pa, the platinum target is pre-evaporated for 10-15 minutes; then, the baffle is opened, the real-time evaporation power is controlled between 200W-300W, and platinum nanometers are evaporated on the baked substrate. particles, the deposition time is 41 seconds; then the samples with platinum nanoparticles deposited are heated to 200-260 °C for 30-60 minutes at a low temperature in a vacuum environment; finally, the annealed multilayer molybdenum disulfide film is naturally cooled in a vacuum environment At room temperature, a molybdenum disulfide film with high indirect bandgap luminescence properties is obtained; it is denoted as Pt-MoS2-6-2.

As a comparative example, at the same time, a molybdenum target (with a molybdenum content of 99.9%) was used as a sputtering source to obtain a molybdenum target, and the sulfur powder (with a sulfur content of 99.9%) and the molybdenum target were prepared by chemical vapor deposition in exactly the same process conditions A pure molybdenum disulfide film was obtained; denoted as MoS2-2.

Test: test the photoluminescence spectra of Pt-MoS2-6-2 and MoS2-2 thin film samples at room temperature respectively; observe Pt-MoS2-6-2 with TEM, and observe and count the size of platinum nanoparticles;

Calculation: Statistics of the peak intensities of Pt-MoS2-6-2 and MoS2 around 1.4eV, which reflect the indirect band gap performance, subtract the respective baselines, which are around 1.65eV, calculate the Pt-MoS2-6-2 phase than the luminous intensity enhancement ratio of MoS2. The results obtained by calculation and TEM particle scale analysis test are shown in Table 6:

Table 6. Indirect bandgap luminescence properties and platinum nanoparticle size of platinum nanoparticles-containing molybdenum disulfide thin films prepared in Example 6

The results show that the indirect bandgap luminescence intensity of the platinum-containing nanoparticle molybdenum disulfide film (PtMoS2-6-2) is 7.2 times higher than that of the pure molybdenum disulfide film (MoS2-2).

Finally, it should be noted that the above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or equivalently replaced. , without departing from the spirit and scope of the present invention, any modification or partial replacement shall be included in the scope of the claims of the present invention.

Claims (1)

1. A method for improving indirect band gap luminescence property of a multilayer molybdenum disulfide film is characterized in that platinum nanoparticles are deposited on the surface of the multilayer molybdenum disulfide film by a magnetron sputtering method, and the particle size of the platinum nanoparticles is smaller than 10 nanometers; the multilayer molybdenum disulfide film is prepared by the following steps:

1) preheating the substrate for 30-45 minutes in a vacuum environment at the temperature of 100-120 ℃;

2) adopting pure argon atmosphere, and pre-sputtering the molybdenum target for 10-15 minutes under the working pressure of 0.5-1.0 Pa;

3) sputtering the preheated substrate in the step 1) by using the molybdenum target which is subjected to the pre-sputtering in the step 2) in the atmosphere of pure argon under the working pressure of 0.5-1.0Pa to deposit a molybdenum film, wherein the thickness of the molybdenum film is 1.8-2.5 nanometers;

4) carrying out chemical vapor deposition on the molybdenum film obtained in the step 3) in a tubular furnace, wherein sulfur powder is arranged at the upstream of a heating source in the tube, the molybdenum film is arranged at the downstream of the heating source in the tube, the gas pressure in the tube is 10-100 Pa, and the flow rate of sulfur steam is kept to be 5-20sccm all the time in the reaction process;

5) preheating the molybdenum film in the step 4) at the temperature of 110-130 ℃ for 50-60 minutes in a vacuum environment, and preheating the sulfur powder in the step 4) at the temperature of 80-100 ℃ for 50-60 minutes;

6) heating the tube furnace in the step 4) to a reaction temperature of 550-750 ℃, wherein the reaction time of the sulfur powder and the molybdenum film is 20-30 minutes, and the annealing time is 60-120 minutes;

the magnetron sputtering method comprises the following specific operation steps:

a) the multilayer molybdenum disulfide film is processed in a background vacuum degree of more than 4 × 10^-3Baking for 15-60 minutes in a sputtering chamber of Pa at the temperature of 100-150 ℃;

b) adopting pure argon atmosphere, and pre-sputtering the platinum target for 10-15 minutes under the working pressure of 6.0-9.0 Pa;

c) adopting pure argon atmosphere, and working at 0.5-1.5Pa and 0.2-1mA/cm²Depositing the platinum nanoparticles on the multilayer molybdenum dioxide film at the target current density for 18-36 seconds;

d) heating the multilayer molybdenum disulfide film deposited with the platinum nano particles obtained in the step c) to 200-260 ℃ in a vacuum environment, and annealing at a low temperature for 30-60 minutes;

e) naturally cooling the multilayer molybdenum disulfide film obtained after low-temperature annealing in the step d) to normal temperature in a vacuum environment;

the mass fraction of molybdenum in the molybdenum target is more than 99.9%, and the mass fraction of sulfur in the sulfur powder is more than 99.9%;

the mass fraction of platinum in the platinum target is 99.9%.

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